Investigation of black spots and other blemishes inside small stainless steel pressure vessels.

摘要

Black spots and other blemishes were found on the inside surface of small stainless steel pressure vessels by borescope inspection. Most of the black spots originated from pyrolysis of lint contaminating the interior surface of these parts prior to welding. The lint originated from cotton gloves used to handle parts and from cotton gauze used to clean the parts. Pyrolysis of other hydrocarbons can also create black spots. 34 figs.